Java8的reduce使用

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public static void main(String[] args) {
        Stream<Integer> stream = Arrays.stream(new Integer[]{1, 2, 3, 4, 5, 6, 7});

        //求集合元素之和
        Integer result = stream.reduce(0, Integer::sum);
        System.out.println(result);

		//求和
        stream = Arrays.stream(new Integer[]{1});
        Integer result2 = stream.reduce(0, (i, j) -> i + j);
        System.out.println("求和:" + result2);
        
        //求和
        stream = Arrays.stream(new Integer[]{1, 2, 3, 4, 5, 6, 7});
        stream.reduce((i, j) -> i + j).ifPresent(System.out::println);

        //求最大值
        stream = Arrays.stream(new Integer[]{1, 2, 3, 4, 5, 6, 7});
        stream.reduce(Integer::max).ifPresent(System.out::println);

        //求最小值
        stream = Arrays.stream(new Integer[]{1, 2, 3, 4, 5, 6, 7});
        stream.reduce(Integer::min).ifPresent(System.out::println);

        //做逻辑运算
        stream = Arrays.stream(new Integer[]{1, 2, 3, 4, 5, 6, 7});
        stream.reduce((i, j) -> i > j ? j : i).ifPresent(System.out::println);

        //求偶数的乘积
        stream = Arrays.stream(new Integer[]{1, 2, 3, 4, 5, 6, 7});
        int result2 = stream.filter(i -> i % 2 == 0).reduce(1, (i, j) -> i * j);

        Optional.of(result2).ifPresent(System.out::println);
    }

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8
求集合元素之和：28
求和:1
28
7
1
1
48